Traditionally, disposable needles have been used with syringes and pen-type injectors and are prevalently used worldwide on reusable or multi-dose devices for invasive delivery of medication. However, because a needle is an invasive device, after a use on a patient, the needle may become a deadly transmitter of infectious diseases, such as Acquired Immune Deficiency Syndrome (AIDS), hepatitis or the like. Thus, replaceable needles present a growing and ever-present health hazard to users in either institutional or home use settings. In addition, used, discarded needles pose a real threat to anyone coming in contact with them
In the past, safe disposal of used needles has been left entirely to the user. For example, conscientious disposal of needles entails an elaborate and often dangerous procedure. First, the needle is unscrewed and removed from the syringe or pen-type injector, then the needle point is manually broken with a specially designed device; and the needle is disposed of in a special canister designed for safe storage and transportation of contaminated waste products. However, this procedure provides numerous opportunities for contact with a used needle and increases the chance of being accidentally stuck by these potentially contaminated needles. Also, the special canister itself, once filled with exposed needle points, is itself a health and safety hazard.